Push button electrical switches



Sept. 30, 1969 E. MILNER E'rAL 3,470,332

y PUSH BUTTON ELECTRICAL SWITCHES mea Feb. 11s. lees @4. o \-r`$rug -J /0/1 A for CU (-3 C7 A 0 0 n 0 D o (44 JJJ-bfnv/2 D 1002/ 2 4 /o 02d 4120 D20 5 no@ UGG Doo 3 f2.9a/f D D D i 8 7 3 ,0% U2U DZ@ D20 J J J .J` .JY Jia) /a 5 'f4/ 1"9 QJ A`f4 b (5 @y 7 9 ya* y AQ ya Qspgreo 9 f3 Q y Q94 /A/VI/VMP ERNEST MILNER ET AL JQMSMS United States Patent() Int. c1. H0111 9/26 U.S. Cl. 200- 8 Claims ABSTRACT 0F THE DISCLOSURE An assembly of push button electrical switcheseach adapted to'give a characteristic switching pattern of an arrangement of electrical contacts, comprising a matrix arrangement of push buttons in rows and columns, and a laterally confined line of movable, abutting, motiontransmitting elements corresponding to each row and column of the matrix, the lines intersecting in a common element corresponding to each push button, each push but- Y ton incorporating deector means for displacingthe elements in the lines corresponding to the row and column it occupies, other than the corresponding common element, and contact means operable by the said displacement to provide the characteristic switching pattern for l each button.

'This invention relates to push button electrical switches, and more particularly to assemblies of such ,switches for use in selecting input signals, e.g., for dialing in telephone handsets, in adding machines, for controlling automatic tools and in computer inputs.

plex and expensive to produce and not wholly reliable.

An object of the invention is to provide more controlled means of selecting numerals which are less complex and less expensive. The ideal device is one which when pressing any selected digit, transmits its motion into longitudinal movement vertically and horizontally, simultaneously operating a number of contact devices, feeding through oscillators of predetermined frequencies to produce a characeristic signal for each depression.

The invention accordingly consists in an assembly of push button electrical switches each adapted to give a characteristic switching pattern of an arrangement of electrical contacts, comprising a matrix arrangement of push buttons in rows and columns, and a laterally confined line of movable, abutting, discrete motion-transmitting elements corresponding to each row and column of the matrix, the lines intersecting in a common element corresponding to each push button, each push button incorporating deflector means for displacing the elements in the lines corresponding to the row and column it occupies, other than the corresponding common element, and contact means operable by the said displacement to provide the characteristic switching pattern for each button.

The displacement of the elements in the lines corresponding to one row and one column acts to displace laterally the common elements of those lines and all other lines, Iand this prevents displacement of the other confined elements in the other, laterally confined lines. Thus the arrangement is interlocking to prevent simultaneous operation of two buttons.

The elements are preferably balls.

l 3,470,332 Patented Sept. 30, 1969 The invention will be further described with reference to a preferred embodiment as illustrated in the accompanying drawings, in which:

FIGURE 1 is a plan view of one form of assembly according to the invention;

FIGURE 2 is an end elevation of the assembly of FIGURE 1;

FIGURE 3 is .a part sectional view of the structure of FIGURE 2, showing one button depressed;

FIGURES 4 and 5 are diagrams illustrating the effect of depressing a push button;

FIGURE 6 is a bottom plan view of one component of the assembly; and

FIGURE 7 is a plan view of the same component.

FIGURES 1 to 3 show the assembly comprising a rectangular back plate 1, a rectangular base 2 and a rectangular cover 3, secured together by bolts or rods 4 set at the'four corners. The cover 3 is apertured to receive twelve push buttons 5 arranged as a matrix of four rows and three columns. As may be seen from FIGURES 2, 3 and 6, the base 2 is formed with open-ended confined channels 6, limited from below by the plate 1, with one channel 6 corresponding to each of the rows and columns of the matrix of push buttons 5. The base 2 is also apertured as shown at 7 adjacent the intersections of the channels 6 (see also FIGURE 7). An upstanding wall 8 spaces the base 2 from the cover 3.

Each channel 6 is of a length to be exactly filled by a line of abutting motion-transmitting balls 9. The arrangement s lsuch that at the intersection of two lines there is a ball 9a common to both.

In a particular embodiment of the invention the balls may be of 1A inch diameter, .and each channel corresponding to a row may contain eleven balls as illustrated in FIGURE 3, whereas each channel corresponding to a column will contain fourteen balls. These figures show diagrammatically spring contact sets 10a and 10b at the ends of the lines of balls 9 corresponding to each row, and similar sets 10c and 10d at the ends of lines of balls 9 corresponding to each column. The inner contact of each set is fairly strongly spring-loaded or inherently resilient to provide the necessary force to return the balls to their normal innermost positions. i

The contact sets 10a may be connected in parallel so as to cause a dialing signal to be heard in the handset whenever a button 5 is pressed in. Contact sets 10b and 10d may each energize a characteristic frequency in the dialing circuit so that each button corresponds to a unique combination of said frequencies. The contact sets 10c have only the function of return springs, but vmay be used as Vcontacts if desired. f

Each push button 5 has a hollow interior which houses a return spring 11 abutting on the base 2 and urging the button outwardly. Movement of the button is limited by abutment of a flange 12 on the inner side of the cover 3 and the facing surface of the base 2. The cover 3 is perforated to allow the buttons to slide freely therethrough. Each button 5 is extended beyond the flange 12 by a set of four fingers 13 which have chamfered camming ends 14 and which extend through the apertures 7 in the .base 2.

The buttons not marked with reference digits may be omitted or used for special calls, e.g., for emergency or internal only calls.

The operation of the device is as follows In the normal position of the assembly the return springs 11 urge all of the buttons to their outward positions and the balls are urged by the inner contacts of the sets to inner positions wherein they do not protrude out from the ends of the channels 6. The contact sets are then in their normal, broken positions as illustrated in FIGURES 1 and 2. FIGURE 4 illustrated the position of the balls at a single intersection between two lines and it can be seen that each ball 9a has two balls 9 adjacent to it in each of the lines. In addition, each ball 9a lies squarely -at the centre of a group of apertures 7.

' Upon depression of any particular button 5 the fingers 13, led by the chamfered ends 14, enter between the corresponding ball 9a and the adjacent balls 9, as illustrated in FIGURES 3 (left-hand button 5) and 5. This causes outward movement of the balls in the two lines corresponding to the row and the column in which lthe particular button stands by a distance equal to the thickness of the fingers 13. This distance is chosen to be less than one half of the diameter of the balls 9, eg., %2 inch, in the case of balls of a 1A inch diameter. The inner contacts of the contact sets at the end of these lines are thus urged loutwardly into the make position as illustrated. The contact set a sets up .a dialing signal in the handset, the sets 10b and 10d combine to energize a frequency characteristie of the button depressed.

In addition, it can be seen from FIGURE 3 that the balls are also pushed so that the balls 9a no longer lie squarely beneath a group of apertures 7. Thus, any button which is common in row or column to the depressed button cannot be depressed since it is blocked by `the balls, and further movement of the balls is also inhibited by the `depressed button. In addition, the movement of buttons which do not lie in the row or column of the depressed button is limited by the fact that the balls in the lines underneath them cannot move owing to the displacement of the common balls 9a, which'efectively block movement of the whole line of balls crossing the moved line. The limited movement which may be possible is insuiiicient to cause operation of the contact sets.

Thus depression of a button gives a characteristic switch pattern, in that each -row and each column only have a single common element, and also depression of a button prevents the depression of any other button until the tirst button is released.

Various modifications may be made 'within the scope of the invention. Thus, while the buttons have been illustrated as of square shape at the operating end, other shapes such as rectangular or circular may be used, and the shape and configuration of the fingers 13 may vary somewhat from the coniiguration illustrated. Also the lengths of the lingers 13, or at least the shaping of the chamfered camming ends 14, from the flange 12, may vary to give a time diierential between the closing of the various contact sets operated. In addition, the depression transmitting elements have been described as being balls. It is clear however that the rolling nature of the transmitting element is not essential, and the balls could be replaced by square section, e.g., cubic, slugs. Further, in certain switching applications, some or all of the make contact sets may be replaced by break sets or change-over sets as required.

' We claim: 1.v In an assembly of push button electrical switches extension ofthe tubular bod-ies.

each adapted to give a characteristic switching pattern of an arrangement of electrical contents, comprising a matrix arrangement of push buttons in rows and columns: the

improvement lthat a laterally confined line of discrete, movable, abutting, motiomtransmitting elements is associated with each of the rows and each of the columns, each push button corresponding to a motion-transmitting element common to the lines associated with the row and column containing the respective push button, each push button comprising deflector meansV for entering between the corresponding common element and the adjacent elements for displacing the elements, other than' the corresponding common element, in the lines associated with the row =and column it occupies, and contact means arranged adjacent the lines and adapted to be operable by the said displacement to provide Ithe switching pattern characteristic of each button, the said-displacement being sufficient to cause the other common elements in the said associated lines to effectively block movement ofthe corresponding push button. j

Z. An assembly as claimed in claim 1, in which the motion-transmitting elements are balls.

3. Anassembly las claimed in claim 1, in which the deector means are in the form of fingers adapted to enter between adjacent motion-transmitting elements.

4. An assembly `as claimed in claim 3, in 'which the fingers have chamfered ends.

5. An assembly as claimed in claim 3, in which the push buttons have tubular bodies and the fingers 'are integral `6. An assembly as claimed in claim 5, comprising a base member supporting the lines of motion-transmitting elements andA having apertures therein through which the fingers protrude.

7. An assembly as claimed in claim 6, comprising springs housed in the tubular bodies and abutting in the base member to bias the push buttons outwards from the base member. j

8. An -assembly as claimed in claim 1, in which the motion-transmitting elements are biased into contact with one another in lines by movable contacts of the contact means.y

References Cited UNITED sTATEs PATENTS ROBERT K. SCHAEFER, Primary Examiner R. A. VANDERHYE, Assistant Examiner U.S`. C1. X.R. 

